Joint Dual-band Crest Factor Reduction and Digital Predistortion of Power Amplifiers Driven by Inter-Band Carrier Aggregated Signals

In this paper, a signal amplitude estimator for inter-band carrier aggregated signals is proposed to assist with the effective application of dual-band crest factor reduction (CFR) and digital predistortion (DPD) for enhanced dual-band power amplifier (PA) performance. As proof of concept validation, the dual-band CFR was applied to reduce the peak to average power ratio of a carrier aggregated signal formed by a 10 MHz LTE signal, centered at 750 MHz, and a 15 MHz LTE signal, centered at 900 MHz, by 2.5 dB while maintaining an error vector magnitude of better than 4 %. The resultant signal was then pre-processed by a dual-band Volterra DPD and used to linearize a 20 W broadband Doherty PA. The joint application of dual-band CFR and DPD succeeded in enhancing the performance of the PA by allowing a linear average output power of about 4 W, and drain efficiency of about 48%, with an adjacent channel leakage ratio of about -50 dBc.